Compliant interconnect assembly

ABSTRACT

An apparatus and method for making a compliant interconnect assembly adapted to electrically couple a first circuit member to a second circuit member. The first dielectric layer has a first major surface and a plurality of through openings. A plurality of electrical traces are positioned against the first major surface of the first dielectric layer. The electric traces include a plurality of conductive compliant members having first distal ends aligned with a plurality of the openings in the first dielectric layer. The first distal ends are adapted to electrically couple with the first circuit member. The second dielectric layer has a first major surface positioned against the electric traces and the first major surface of the first dielectric layer. The second dielectric layer has a plurality of through openings through which the electric traces electrically couple with the second circuit member.

REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/453,322 filed Jun. 3, 2003 entitled “Compliant InterconnectAssembly”, which is a continuation-in-part application of U.S. patentapplication Ser. No. 10/169,431 filed Jun. 26, 2002 entitled “FlexibleCompliant Interconnect Assembly”, which claims priority toPCT/US01/00872 filed Jan. 11, 2001, which claims the benefit of U.S.provisional application Ser. No. 60/177,112 filed Jan. 20, 2000, all ofwhich are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is directed to a method and apparatus forachieving a compliant, solderless or soldered interconnect betweencircuit members.

BACKGROUND OF THE INVENTION

The current trend in connector design for those connectors utilized inthe computer field is to provide both high density and high reliabilityconnectors between various circuit devices. High reliability for suchconnections is essential due to potential system failure caused bymisconnection of devices. Further, to assure effective repair, upgrade,testing and/or replacement of various components, such as connectors,cards, chips, boards, and modules, it is highly desirable that suchconnections be separable and reconnectable in the final product.

Pin-type connectors soldered into plated through holes or vias are amongthe most commonly used in the industry today. Pins on the connector bodyare inserted through plated holes or vias on a printed circuit board andsoldered in place using conventional means. Another connector or apackaged semiconductor device is then inserted and retained by theconnector body by mechanical interference or friction. The tin leadalloy solder and associated chemicals used throughout the process ofsoldering these connectors to the printed circuit board have come underincreased scrutiny due to their environmental impact. Additionally, theplastic housings of these connectors undergo a significant amount ofthermal activity during the soldering process, which stresses thecomponent and threatens reliability.

The soldered contacts on the connector body are typically the means ofsupporting the device being interfaced by the connector and are subjectto fatigue, stress deformation, solder bridging, and co-planarityerrors, potentially causing premature failure or loss of continuity. Inparticular, as the mating connector or semiconductor device is insertedand removed from the present connector, the elastic limit on thecontacts soldered to the circuit board may be exceeded causing a loss ofcontinuity. These connectors are typically not reliable for more than afew insertions and removals of devices. These devices also have arelatively long electrical length that can degrade system performance,especially for high frequency or low power components. The pitch orseparation between adjacent device leads that can be produced usingthese connectors is also limited due to the risk of shorting.

Another electrical interconnection method is known as wire bonding,which involves the mechanical or thermal compression of a soft metalwire, such as gold, from one circuit to another. Such bonding, however,does not lend itself readily to high-density connections because ofpossible wire breakage and accompanying mechanical difficulties in wirehandling.

An alternate electrical interconnection technique involves placement ofsolder balls or the like between respective circuit elements. The solderis reflown to form the electrical interconnection. While this techniquehas proven successful in providing high-density interconnections forvarious structures, this technique does not facilitate separation andsubsequent reconnection of the circuit members.

An elastomeric material having a plurality of conductive paths has alsobeen used as an interconnection device. The conductive elements embeddedin the elastomeric sheet provide an electrical connection between twoopposing terminals brought into contact with the elastomeric sheet. Theelastomeric material must be compressed to achieve and maintain anelectrical connection, requiring a relatively high force per contact toachieve adequate electrical connection, exacerbating non-planaritybetween mating surfaces. Location of the conductive elements isgenerally not controllable. Elastomeric connectors may also exhibit arelatively high electrical resistance through the interconnectionbetween the associated circuit elements. The interconnection with thecircuit elements can be sensitive to dust, debris, oxidation,temperature fluctuations, vibration, and other environmental elementsthat may adversely affect the connection.

The problems associated with connector design are multiplied whenmultiple integrated circuit devices are packaged together in functionalgroups. The traditional way is to solder the components to a printedcircuit board, flex circuit, or ceramic substrate in either a bare diesilicon integrated circuit form or packaged form. Multi-chip modules,ball grids, array packaging, and chip scale packaging have evolved toallow multiple integrated circuit devices to be interconnected in agroup.

One of the major issues regarding these technologies is the difficultyin soldering the components, while ensuring that reject conditions donot exist. Many of these devices rely on balls of solder attached to theunderside of the integrated circuit device which is then reflown toconnect with surface mount pads of the printed circuit board, flexcircuit, or ceramic substrate. In some circumstances, these joints aregenerally not very reliable or easy to inspect for defects. The processto remove and repair a damaged or defective device is costly and manytimes results in unusable electronic components and damage to othercomponents in the functional group.

Many of the problems encountered with connecting integrated circuitdevices to larger circuit assemblies are compounded in multi-chipmodules. Multi-chip modules have had slow acceptance in the industry dueto the lack of large scale known good die for integrated circuits thathave been tested and burned-in at the silicon level. These dies are thenmounted to a substrate, which interconnect several components. As thenumber of devices increases, the probability of failure increasesdramatically. With the chance of one device failing in some way andeffective means of repairing or replacing currently unavailable, yieldrates have been low and the manufacturing costs high.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a method and apparatus forachieving a fine pitch interconnect between first and second circuitmembers. The connection with the first and second circuit members can besoldered or solderless. The circuit members can be printed circuitboards, another flexible circuit, a bare-die device, an integratedcircuit device, an organic or inorganic substrate, a rigid circuit andvirtually any other type of electrical component.

In one embodiment, compliant interconnect assembly include a firstdielectric layer having a first major surface and a plurality of throughopenings. A plurality of electrical traces are positioned against thefirst major surface of the first dielectric layer. The electric tracesinclude a plurality of conductive compliant members having first distalends aligned with a plurality of the openings in the first dielectriclayer. The first distal ends are adapted to electrically couple with thefirst circuit member. The second dielectric layer has a first majorsurface positioned against the electric traces and the first majorsurface of the first dielectric layer. The second dielectric layer has aplurality of through openings through which the electric traceselectrically couple with the second circuit member.

In one embodiment, at least a portion of the first distal ends aredeformed to project through an opening in the first dielectric layer. Inanother embodiment, at least a portion of the first distal ends extendabove a second major surface of the first dielectric layer. In oneembodiment, at least a portion of the first distal ends comprise aplurality of distal ends. In yet another embodiment, at least a portionof the first distal end comprises a curvilinear shape. At least aportion of the conductive compliant members preferably have seconddistal ends aligned with a plurality of the openings in the seconddielectric layer to electrically couple with the second circuit member.

The electrical traces can optionally be attached to the first majorsurface of the first dielectric layer or to a flexible circuit member.In one embodiment, a solder ball is attached to the electrical traces toelectrically couple with the second circuit member.

In some embodiments, an additional circuitry plane is attached to asecond major surface of the second dielectric layer. The additionalcircuitry plane comprises a plurality of through openings aligned with aplurality of the through openings in the second dielectric layer. Theadditional circuitry plane can be one of a ground plane, a power plane,or an electrical connection to other circuit members. One or morediscrete electrical components are optionally electrically coupled tothe electrical traces.

The electrical traces are preferably singulated so that a portion of theconductive compliant members are electrically isolated from theelectrical traces. In one embodiment, a portion of the conductivecompliant members are electrically coupled to form a ground plane or apower plane.

The first distal ends of the conductive compliant members are preferablyadapted to engage with a connector member selected from the groupconsisting of a flexible circuit, a ribbon connector, a cable, a printedcircuit board, a ball grid array (BGA), a land grid array (LGA), aplastic leaded chip carrier (PLCC), a pin grid array (PGA), a smalloutline integrated circuit (SOIC), a dual in-line package (DIP), a quadflat package (QFP), a leadless chip carrier (LCC), a chip scale package(CSP), or packaged or unpackaged integrated circuits.

In one embodiment, the second dielectric layer is attached to a printedcircuit board and a plurality of the conductive compliant members areelectrically coupled to contact pads on the printed circuit boardthrough the openings in the second dielectric layer. In anotherembodiment, a portion of the first electrical traces extend beyond thecompliant interconnect assembly to form a stacked configuration othercompliant interconnect assemblies. The dielectric layers can be rigid orflexible.

In one embodiment, the plurality of electrical traces includes a firstset of electrical traces having a plurality of conductive compliantmembers having first distal ends aligned with a plurality of openings inthe first dielectric layer. A second set of electrical traces having aplurality of conductive compliant members having second distal ends arealigned with a plurality of openings in the second dielectric layer. Anelectrical connection is formed between one or more of the conductivecompliant members on the first set of electrical traces and one or moreof the conductive compliant members on the second set of electricaltraces.

A dielectric layer is optionally located between the first and secondsets of electrical traces. The electrical connection can be one ofsolder, a conductive plug, a conductive rivet, conductive adhesive, aheat stake, spot weld, and ultrasonic weld, a compression joint, orelectrical plating. An additional circuitry plane is optionally locatedbetween the first and second sets of electrical traces. One or morediscrete electrical components are optionally located between the firstand second sets of electrical traces.

The first and second circuit member can be one of a printed circuitboard, a flexible circuit, a bare die device, an integrated circuitdevice, organic or inorganic substrates, or a rigid circuit.

The present invention is also directed to a method of making a compliantinterconnect assembly. A plurality of electrical traces are positionedagainst the first major surface of a first dielectric layer, theelectric traces comprising a plurality of conductive compliant membershaving first distal ends aligned with a plurality of through openings inthe first dielectric layer. A first major surface of a second dielectriclayer is positioned against the electric traces and the first majorsurface of the first dielectric layer. The second dielectric layer has aplurality of through openings. The first distal ends are electricallycoupled to the first circuit member. The second circuit member iselectrically coupled to a second circuit member through the openings inthe second dielectric layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a substrate used for making a compliant interconnect inaccordance with the present invention.

FIG. 2 is a side sectional of the substrate of FIG. 1 with a maskingmaterial applied in accordance with the present invention.

FIG. 3 is a side sectional view of the substrate and masking material ofFIG. 2 with an additional hole in accordance with the present invention.

FIG. 4 is a side sectional view of a compliant material applied to thesubstrate of FIG. 3.

FIG. 3 is a side sectional view of a method of modifying the electricalinterconnect of FIG. 2.

FIG. 4 is a side sectional view of an electrical contact modified inaccordance with the method of the present invention.

FIG. 5 is a side sectional view of a compliant interconnect assembly inaccordance with the present invention.

FIG. 6 is a side sectional view of the compliant interconnect assemblyof FIG. 5 in a compressed state in accordance with the presentinvention.

FIGS. 7-9 are side sectional views of an alternate compliantinterconnect in accordance with the present invention.

FIG. 10A is a perspective view of a flexible circuit member inaccordance with the present invention.

FIG. 10B is a perspective view of an alternate flexible circuit memberin accordance with the present invention.

FIG. 10C is a perspective view of another alternate flexible circuitmember in accordance with the present invention.

FIG. 10D is a top view of electrical traces of a flexible circuit memberprior to singulation.

FIG. 10E is a top view of the flexible circuit member of FIG. 10D aftersingulation.

FIG. 10F is a top view of electrical traces of a flexible circuit memberprior to singulation.

FIG. 10G is a top view of electrical traces of a flexible circuit memberprior to singulation.

FIG. 10H is a top view of electrical traces of a flexible circuit memberprior to singulation.

FIG. 101 is a top view of electrical traces of a flexible circuit memberprior to singulation.

FIG. 11 is a side sectional view of a compliant interconnect assembly inaccordance with the present invention.

FIG. 12A is a side sectional view of an alternate compliant interconnectassembly in a stacked configuration in accordance with the presentinvention.

FIG. 12B is a side sectional view of an alternate compliant interconnectassembly with a spring member in accordance with the present invention.

FIG. 12C is a side sectional view of an alternate compliant interconnectassembly with a sheet of spring members in accordance with the presentinvention.

FIG. 12D is a side sectional view of an alternate compliant interconnectassembly using one of the flexible circuit members of FIGS. 10D-10I.

FIG. 13 is a side sectional view of an alternate compliant interconnectassembly with a carrier in accordance with the present invention.

FIG. 14A is a side sectional view of a compliant interconnect assemblyon an integrated circuit device in accordance with the presentinvention.

FIG. 14B is a side sectional view of an alternate compliant interconnectassembly on an integrated circuit device in accordance with the presentinvention.

FIG. 15A is a side sectional view of a compliant interconnect assemblywith a carrier and an integrated circuit device in accordance with thepresent invention.

FIG. 15B is a side sectional view of a compliant interconnect assemblypackaged with an integrated circuit device in accordance with thepresent invention.

FIG. 16 is a replaceable chip module using the compliant interconnectassembly in accordance with the present invention.

FIG. 17 is a side sectional view of a plurality of compliantinterconnect assemblies in a stacked configuration in accordance withthe present invention.

FIG. 18 is a top view of a compliant interconnect assembly with theflexible circuit members extending therefrom in accordance with thepresent invention.

FIG. 19 is a side sectional view of a plurality of circuit members in astacked configuration coupled using a compliant interconnect assembly inaccordance with the present invention.

FIG. 20 is a side sectional view of various structures on a flexiblecircuit member for electrically coupling with a circuit member.

FIG. 21 is a side sectional view of an alternate compliant interconnectassembly using one of the flexible circuit members of FIGS. 10D-10I.

FIG. 22 is a side sectional view of an alternate compliant interconnectassembly using one of the flexible circuit members of FIGS. 10F-10I.

FIG. 23 is a side sectional view of an alternate compliant interconnectassembly using a pair of the flexible circuit members, such asillustrated in FIGS. 10D-10I, in a back to back configuration.

FIG. 24 is a side sectional view of an alternate compliant interconnectassembly using a pair of the flexible circuit members, such asillustrated in FIGS. 10D-10I, in a back to back configuration.

FIG. 25 illustrates an alternate compliant interconnect assemblygenerally as illustrated in FIG. 21 with an additional circuitry planeis added to the structure.

FIG. 26 illustrates an alternate compliant interconnect assemblygenerally as illustrated in FIG. 24 with an additional circuitry planeis added to the structure.

FIG. 27 illustrates an alternate compliant interconnect assemblygenerally as illustrated in FIG. 21 with an additional circuitry planeis added to the structure.

FIGS. 28A-28D illustrate an alternate compliant interconnect assemblyconstructed with a plurality of discrete compliant members.

FIG. 29 illustrate a variation of the compliant interconnect assembly ofFIG. 28A.

FIG. 30 is a top view of a compliant interconnect assembly generally asillustrated in FIGS. 21-29.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-4 illustrate a method of preparing a compliant interconnect 22in accordance with the present invention (see FIG. 5). The Figuresdisclosed herein may or may not be drawn to scale. The substrate 20 isperforated to include one or more through holes 24. The holes 24 can beformed by a variety of techniques, such as molding, stamping, laserdrilling, or mechanical drilling. The holes 24 can be arranged in avariety of configurations, including one or two-dimensional arrays. Aswill be discussed below, some embodiments do not require the holes 24.The substrate 20 is typically constructed from a dielectric material,such as plastics, ceramic, or metal with a non-conductive coating. Insome of the embodiments discussed below, an electrically active circuitmember (see FIG. 11) is substituted for the electrically inactivesubstrate 20.

As illustrated in FIG. 2, the substrate 20 is then flooded with one ormore masking materials 26, such as a solder mask or other materials.Through careful application and/or subsequent processing, such asplanarization, the thickness of the masking material at locations 28, 30is closely controlled for reasons that will become clearer below. Theadditional holes 32 shown in FIG. 3 are then drilled or perforated inthe substrate 20 and masking material 24 at a predetermined distance 36from the existing through hole 24. While there is typically a hole 32adjacent each of the holes 24, there is not necessarily a one-to-onecorrelation. The holes 32 can be arranged in a variety ofconfigurations, which may or may not correlate to the one ortwo-dimensional array of holes 24.

The holes 32 are then filled with a compliant material 38, as shown inFIG. 4. The thickness of the compliant material 38 is typicallydetermined by the thickness of the masking material 26. Suitablecompliant materials include elastomeric materials such as Sylgard™available from Dow Corning Silicone of Midland, Mich. and MasterSyl'713, available from Master Bond Silicone of Hackensack, N.J.

The compliant interconnect 22 of FIGS. 2-4 can optionally be subjectedto a precision grinding operation, which results in very flat surfaces,typically within about 0.0005 inches. The grinding operation can beperformed on both sides at the same time using a lapping or doublegrinding process. In an alternate embodiment, only one surface of thecompliant interconnect 22 is subject to the planarization operation. Thepresent method permits the accurate manufacture of raised portions 40having virtually any height.

Once the compliant encapsulant 38 is cured, the masking material 26 isremoved to yield the compliant interconnect 22 illustrated in FIG. 5.The compliant interconnect 22 illustrated in FIG. 5 includes thesubstrate 20, one or more compliant raised portions 40 of the compliantencapsulant 38 extending above the substrate 20, and the through holes24. The compliant raised portions can be, for example, thenon-conductive encapsulant 38 in FIG. 5 or the conductive member 171C ofFIG. 12C. The substrate can be a carrier or a circuit member, such as aprinted circuit board, a flexible circuit, a bare die device, anintegrated circuit device, organic or inorganic substrates, or a rigidcircuit. The through holes are optionally added for some applications.

FIG. 5 illustrates a compliant interconnect assembly 34 in accordancewith the present invention. The compliant interconnect assembly 34includes the compliant interconnect 22 and one or more flexible circuitmembers 50, 70. The first flexible circuit member 50 is located alongone surface of the compliant interconnect 22. The first flexible circuitmember 50 includes a polymeric sheet 52 and a series of electricaltraces 54. In the embodiment illustrated in FIG. 5, the traces 54terminate at a contact pad 56. The electrical trace 54 terminates in asolder ball 64. The contact pad 56 is positioned to engage with acontact pad 60 on a first circuit member 62. The solder ball 64 ispositioned adjacent to through hole 65. As used herein, “circuit member”refers to a printed circuit board, a flexible circuit, a packaged orunpackaged bare die silicon device, an integrated circuit device,organic or inorganic substrates, a rigid circuit, or a carrier(discussed below).

The region of the polymeric sheet 52 adjacent to the contact pad 56includes singulation 58. The singulation 58 is a complete or partialseparation of the terminal from the sheet 52 that does not disrupt theelectrical integrity of the conductive trace 54. In the illustratedembodiment, the singulation 58 is a slit surrounding a portion of thecontact pad 56. The slit may be located adjacent to the perimeter of thecontact pad 56 or offset therefrom. The singulated flexible circuitmembers 50, 70 control the amount of force, the range of motion, andassist with creating a more evenly distributed force vs. deflectionprofile across the array.

As used herein, a singulation can be a complete or partial separation ora perforation in the polymeric sheet and/or the electrical traces.Alternatively, singulation may include a thinning or location ofweakness of the polymeric sheet along the edge of, or directly behind,the contact pad. The singulation releases or separates the contact padfrom the polymeric sheet, while maintaining the interconnecting circuittraces.

The singulations can be formed at the time of manufacture of thepolymeric sheet or can be subsequently patterned by mechanical methodssuch as stamping or cutting, chemical methods such as photolithography,electrical methods such as excess current to break a connection, alaser, or a variety of other techniques. In one embodiment, a lasersystem, such as Excimer, CO₂, or YAG, creates the singulation. Thisstructure is advantageous in several ways, where the force of movementis greatly reduced since the flexible circuit member is no longer acontinuous membrane, but a series of flaps or bond sites with a livinghinge and bonded contact (see for example FIG. 10).

The second flexible circuit member 70 is likewise positioned on theopposite side of the compliant interconnect 22. Electrical trace 72 iselectrically coupled to contact pad 74 positioned to engage with acontact pad 76 on a second circuit member 78. Solder ball 80 is locatedon the opposite end of the electrical trace 72. Polymeric sheet 82 ofthe second flexible circuit member 70 also includes a singulation 84adjacent to the contact pad 74.

The contact pads 56, 74 can be part of the base laminate of the flexiblecircuit members 50, 70, respectively. Alternatively, discrete contactpads 56, 74 can be formed separate from the flexible circuit members 50,70 and subsequently laminated or bonded in place. For example, an arrayof contact pads 56, 74 can be formed on a separate sheet and laminatedto the flexible circuit members 50, 70. The laminated contact pads 56,74 can be subsequently processed to add structures (see FIG. 20) and/orsingulated.

The contact pads 60, 76 may be a variety of structures such as, forexample, a ball grid array, a land grid array, a pin grid array, contactpoints on a bare die device, etc. The contact pads 60, 76 can beelectrically coupled with the compliant interconnect assembly 34 bycompressing the components 62, 78, 34 together (solderless), byreflowing solder or solder paste at the electrical interface, byconductive adhesive at the electrical interface, or a combinationthereof.

As illustrated in FIG. 6, the first and second flexible circuit members50, 70 are compressed against the compliant interconnect assembly 34.The solder balls 64, 80 are reflown and create an electrical connectionbetween the first and second flexible circuit members 50, 70, generallywithin through hole 65. Adhesive 90 may optionally be used to retain thefirst and second flexible circuit members 50, 70 to the substrate 20.Contact pads 56, 74 are abutted against raised portion 40 of thecompliant material 38.

The singulations 58, 84 permit the raised portions 40 to push thecontact pads 56, 74 above the surface of the substrate 20, withoutdamaging the first and second flexible circuit members 50, 70,respectively. The raised portion 40 also deforms outward due to beingcompressed. The contact pads 56, 74 may optionally be bonded to theraised compliant material 40. The raised compliant material 40 supportsthe flexible circuit members 50, 70, and provides a contact force thatpresses the contact pads 56, 74 against the contact pads 60, 76 as thefirst and second circuit members 62, 78, respectively are compressedagainst the compliant interconnect assembly 34. The movement of thecontact pads 56, 74 is controlled by the raised portion 40 of thecompliant material 38 and the resiliency of the flexible circuit members50, 70. These components are engineered to provide a desired level ofcompliance. The raised portions 40 provide a relatively large range ofcompliance of the contact pads 56, 74. The nature of the flexiblecircuit members 50, 70 allow fine pitch interconnect and signal escaperouting, but also inherently provides a mechanism for compliance.

In the illustrated embodiment, the electric trace 54 extends betweensolder ball 64 and contact pad 56. Similarly, the electric trace 72extends between the solder ball 80 and the contact pad 74. Consequently,the compliant interconnect assembly 34 operates as a pass-throughconnector between the contact pad 60 on the first circuit member 62 andthe contact pad 76 on the second circuit member 78.

FIG. 7 illustrates an alternate substrate 100 with an array of throughholes 102. In the illustrated embodiment, masking material 104 isapplied to only one surface of the substrate 100 and the through hole102. Additional holes 106 are prepared in the masking material 104 andsubstrate 100 a fixed distance 108 from the hole 102, as illustrated inFIG. 8. The hole 106 is only drilled partially into the substrate 100. Acompliant material 110 is then deposited in the hole 106. After themasking material 104 is removed, the resulting compliant interconnect112 includes a raised compliant material only on one surface (seegenerally FIG. 1).

FIG. 10A is a perspective view of a flexible circuit member 120Asuitable for use in the present invention. The flexible circuit member120A includes a series of electrical traces 122A deposited on apolymeric sheet 124A and terminating at an array of contact pads orterminals 126A. As used herein “terminal” refers to an electricalcontact location or contact pad. In the illustrated embodiment, theterminals 126A include a singulation 128A. The degree of singulation128A can vary depending upon the application. For example, in someembodiments the flexible circuit member 120A stretches in order tocomply with the raised portions. In other embodiments a greater degreeof singulation minimizes or eliminates stretching of the flexiblecircuit member 120A due to engagement with the raised portions.

In some embodiments, the terminals 126A include one or more locations ofweakness 130A. As used herein, “locations of weakness” include cuts,slits, perforations or frangible portions, typically formed in thepolymeric sheet 124A and/or a portion of the electrical trace 122Aforming the terminal 126A. The locations of weakness facilitateinterengagement of an electrical contact, such as a ball contact on aBGA device, with the terminal 126A (see FIG. 19). The terminals 126A canoptionally include an aperture 132A to further facilitate engagementwith an electrical contact. In another embodiment, a portion 134A of thetrace 122A protrudes into the aperture 132A to enhance electricalengagement with the electrical contact.

In other embodiments, a compliant raise portion is attached to the rearof the flexible circuit member 120A opposite the terminal 126A (see FIG.11). When the flexible circuit member 120A is pressed against a surface(such as a printed circuit board), the raised compliant material liftsthe singulated terminal 126A away from the surface.

FIG. 10B is a top plan view of an alternate flexible circuit member 120Bwith an elongated singulation 128B. Contact pads 126B are located on thetop of the polymeric sheeting 124B and the solder ball bonding sites125B are located on the bottom. The contact pads 126B are offset fromthe solder ball-bonding site 125B by the portion 127B of the polymericsheeting 124B. An electrical trace can optionally connect the contactpads 125B with the contact pads 126B along the portion 127B. The portion127B permits the contact pads 126B to be raised up or deflected from theflexible circuit member 120B in order to comply with the motion of theflexure (see for example FIGS. 11-15) with minimal or no deformation orstretching of the surrounding polymeric sheeting 124B. The contact pads126B can optionally include locations of weakness.

FIG. 10C is a top plan view of an alternate flexible circuit member 120Cwith an irregularly shaped singulation 128C. Contact pads 126C arelocated on the top of the polymeric sheeting 124C and the solder ballbonding sites 125C are located on the bottom. The contact pads 126C areoffset from the solder ball-bonding site 125C by the irregularly shapedportion 127C of the polymeric sheeting 124C. The shape of the portion127C determines the force required to raise up or deflect the contactpads 126C from the flexible circuit member 120C in order to comply withthe motion of the flexure (see for example FIGS. 11-15). Again, minimalor no deformation or stretching of the surrounding polymeric sheeting124C is experienced. An electrical trace 121C can optionally connectsome of the contact pads 125C with the contact pads 126C along theportion 127C. Additionally, trace 129C can connect two or more contactpads 125C, such as for a common ground plane.

FIG. 10D is a top plan view of a pattern of electrical traces 122D of aflexible circuit member 120D prior to singulation. In the embodiment ofFIG. 10D, the electrical traces 122D include tie bars 124Dinterconnecting a plurality of compliant members 126D. As will bediscussed below, distal ends 128D of the compliant members 126D can beeasily deformed out of the plane of the tie bars 124D to electricallycouple with other circuit members. For example, the distal ends 128D areconfigured to electrically couple with contact pads on an LGA device,while proximal ends 130D can electrically couple with a BGA device.Although the distal end 128D is generally linear, it can be configuredwith a variety of non-linear features, such as curvilinear or serpentineportions (see e.g., FIGS. 10F-10I). The electrical traces 122D arepreferably constructed from a copper alloy formed by chemical etching,laser ablation, mechanical stamping or a variety of other techniques.

The electrical traces 122D can optionally be attached to a polymericsheet, such as illustrated in FIGS. 10A-10C. In another embodiment, theelectrical traces 122D are attached to a carrier, such as illustrated inFIG. 12C. The carrier can be rigid, semi-rigid, or flexible. Theelectrical traces 122D can be attached to a carrier using a variety oftechniques, such as lamination with or without adhesives, over molding,insert molding, and a variety of other techniques. In some embodiments,portions of the electrical traces 122D are sufficiently thick to operateas freestanding compliant members, such as illustrated in FIG. 12B.

In the preferred embodiment, the electrical traces 122D are supported bya carrier that maintains the relative position of the individualcompliant members 126D after singulation. Singulation is typicallyaccomplished by cutting or removing selected tie bars 124D usingchemical etching, laser ablation or mechanical processes. One advantageof the present embodiment is the ability to process an entire field ofcompliant members 126D as a group. Many different geometries ofelectrical traces 122D are possible and are shaped based upon the typeof terminal to which it must connect.

FIG. 10E is a top plan view of a pattern of electrical traces 122D of aflexible circuit member 120D of FIG. 10D after singulation. Theelectrical traces 122D are attached to a carrier (see e.g. FIG. 21) sothat the relative position of the compliant members 126D remainssubstantially unchanged even if all tie bars 124D are removed duringsingulation. In the embodiment illustrated in FIG. 10E, selected tiebars 124D are removed by chemical etching or laser ablation. Thecompliant members 132D connected by tie bars 124D form a ground plane orpower plane. The compliant members 134D that are disconnected from theelectrical traces 122D (i.e., discrete compliant members) typicallycarry electrical signals between the first and second circuit members(see FIG. 21).

FIG. 10F is a top plan view of a pattern of electrical traces 122F of aflexible circuit member 120F prior to singulation. The electrical traces122F include tie bars 124F interconnecting a plurality of compliantmembers 126F. In the embodiment of FIG. 10F, each compliant member 126Fincludes a pair of distal ends 128F, 130F. The distal ends 128F, 130F ofthe compliant members 126F can be easily deformed out of the plane ofthe tie bars 124F to electrically couple with other circuit members. Thedistal ends 128F, 130F can be deformed in the same or differentdirections, depending upon the application (see e.g., FIG. 22). Thecurved portions 132F, 134F of the distal ends 128F, 130F areparticularly well suited to electrically couple with a BGA device. Thecurved portions 132F, 134F are adapted to create a snap-fit attachmentto a ball on BGA circuit member. Members 136F, 138F on the inside edgeof the curved portions 132F, 134F facilitate electrical coupling to aBGA device.

FIG. 10G is a top plan view of a pattern of electrical traces 122G of aflexible circuit member 120G prior to singulation. Each compliant member126G includes a pair of distal ends 128G, 130G. The distal ends 128G,130G of the compliant members 126G can be easily deformed out of theplane of the tie bars 124G to electrically couple with other circuitmembers.

FIG. 10H similarly shows a top plan view of a pattern of electricaltraces 122H of a flexible circuit member 120H prior to singulation.

Each compliant member 126H includes a pair of distal ends 128H, 130H.

FIG. 11 is a top plan view of a pattern of electrical traces 1221 whereeach compliant member 1261 includes a pair of curved distal ends 1281,1301. The curved portions 1321, 1341 of the distal ends 1281, 1301 areparticularly well suited to electrically couple with a BGA device. Thecurved portions 1321, 1341 are adapted to create a snap-fit attachmentto a ball on BGA circuit member.

FIG. 11 is a sectional view of an alternate compliant interconnectassembly 140 in accordance with the present invention. The raisedcompliant material 142 is formed directly on second circuit member 144,which in the embodiment of FIG. 11 is a printed circuit board. In analternate embodiment, the raised compliant material 142 are formedseparate from the second circuit member 144 and subsequently bondedthereto using a suitable adhesive or other bonding technique. In anotherembodiment, the raised portion 142 is formed on, or bonded to, the rearof flexible circuit member 146. In the illustrated embodiment, theprinted circuit board 144 serves the function of both the substrate 20and the second circuit member 78 illustrated in FIG. 5. The embodimentof FIG. 11 does not require through holes in the circuit member 144.

Flexible circuit member 146 includes a solder ball 148 that is typicallyreflown to electrically couple bonding pad 150 to the contact pad 152 onthe circuit board 144. Alternatively, solder paste can be applied toboth the bonding pad 150 and the contact pad 152. Electrical trace 154electrically couples the solder bonding pad 150 to contact pad 156.Contact pad 156 may optionally include a rough surface to enhance theelectrical coupling with the contact pad 160 on the first circuit member162. The flexible circuit member 146 is singulated so that the raisedcompliant material 142 lifts the contact pad 156 away from the circuitmember 144. When the circuit member 162 is compressed against thecompliant interconnect assembly 140, the raised compliant material 142biases the contact pad 156 against the first circuit member 162. In thecompressed state, the compliant interconnect assembly 140 can have aheight of about 0.3 millimeters or less. Alternatively, the contact pad160 can be electrically coupled with the contact pad 156 by reflowingsolder or solder paste at the electrical interface, by conductiveadhesive at the electrical interface, or either of the above incombination with compression.

The raised compliant material 142 can optionally be doped or filled withrigid or semi-rigid materials to enhance the integrity of the electricalcontact created with the contact pad 160 on the first circuit member162. Bonding layer 164 is optionally provided to retain the contact pad156 to the raised compliant material 142.

FIG. 12A illustrates an alternate compliant interconnect assembly 170using a compliant interconnect generally as illustrated in FIGS. 7-9.Raised compliant material 172 is attached to a carrier 174 that isinterposed between first and second circuit members 176, 178. Thecarrier 174 can be rigid or flexible. An additional support layer 182can optionally be added to the carrier 174 to increase rigidity and/orcompliance. In one embodiment, the raised compliant material 172 has afirst modulus of elasticity and the additional support layer 182 has asecond modulus of elasticity different from the first modulus ofelasticity. In another embodiment, the raised compliant material 172 isattached to the rear surface of flexible circuit member 184.

Flexible circuit member 184 is electrically coupled to the contact pad186 on second circuit member 178 by solder ball or solder paste 188.When the first circuit member 176 is compressively engaged with thecompliant interconnect assembly 170, raised compliant material 172biases contact pad 190 on the flexible circuit member 184 againstcontact pad 192 on the first circuit member 176. In an embodiment wherethe carrier 174 has compliant properties, the combined compliantproperties of the carrier 174 and raised compliant material 172 providesthe bias force.

In another embodiment, the flexible circuit member 184 extends to asecond interconnect assembly 170A. Any of the interconnect assembliesdisclosed herein can be used as the interconnect assembly 170A. In theillustrated embodiment, raised compliant material 172A is attached to acarrier 174A that is interposed between first circuit members 176 and athird circuit member 194. The carrier 174A can be rigid or flexible. Anadditional support layer 182A can optionally be added to the carrier174A to increase rigidity and/or compliance. The third circuit member194 can be an integrated circuit device, such as the LGA deviceillustrated in FIG. 12A, a PCB or a variety of other devices. The entireassembly of circuit members 176, 178, 194 can be stacked together andthe solder then mass reflowed during final assembly.

FIG. 12B illustrates an alternate compliant interconnect assembly 170Bgenerally as illustrated in FIG. 12A, except that the raised compliantmaterial 172B attached to a carrier 174B is an elongated compliantmember 171B. The compliant member 171B can be spring member or a rigidmember attached to a compliant carrier 174B, such as a beryllium copperspring. An additional support layer 182B can optionally be added to thecarrier 174B to increase rigidity and/or compliance. The compliantmembers 171B provide reactive support to urge the contact pad 190B onthe flexible circuit member 184B against the contact pad 192B on thefirst circuit member 176B. The compliant member 171B can be formed inthe carrier 174B or formed separately and attached thereto. Thecompliant member 171B can alternatively be a coil spring or a variety ofother structures.

FIG. 12C illustrates another alternate compliant interconnect assembly170C generally as illustrated in FIG. 12B, except that the raisedcompliant material 172C is an elongated compliant member 171C supportingthe flexible circuit member 184C. Substrate 174C includes a series ofcompliant spring members 171C positioned under the flexible circuitmember 184C. The upper surface of the flexible circuit member 184C ispatterned with a series of rough contact pads 190C. The lower surface ofthe flexible circuit member 184C is prepared to receive solder paste orsolder ball 194C. The rigid substrate 174C also includes a series ofsolder deposit alignment openings 175C through which solder ball 194Ccan couple the lower surface of the flexible circuit member 184C withsecond circuit member 198C. The compliant members 171C provide reactivesupport to bias the flexible circuit member 184C against contact pad192C on first circuit member 176C.

FIG. 12D illustrates another alternate compliant interconnect assembly170D generally as illustrated in FIG. 12C, except that the raisedcompliant material 172D operates without the polymeric sheeting of aflexible circuit member. The thickness of the compliant member 172D canbe engineered to provide the desired amount of resiliency. Substrate174D includes a series of conductive compliant members 171D positionedto engage with the contact pad 192D on the first circuit member 176D.The lower surface of the conductive compliant member 171D is prepared toreceive solder paste or solder ball 194D. The substrate 174D alsoincludes a series of solder deposit alignment openings 175D throughwhich solder ball 194D can couple the lower surface of the conductivecompliant members 171D with second circuit member 198D.

FIG. 13 illustrates an alternate compliant interconnect assembly 200 inaccordance with the present invention. A pair of discrete compliantraised portions 202, 204 are attached to a carrier 206. In theillustrated embodiment, the carrier 206 is a multi-layered structure.First and second flexible circuit members 210, 212 are positioned onopposite sides of the compliant interconnect assembly 200, generally asillustrated in FIG. 6. Solder ball 214 connects solder ball pads 216,218 on the respective flexible circuit members 210, 212. The solder ball214 can be replaced by a variety of connection methods such as wedgebonding, ultrasonic bonding, resistance bonding, wire bonding, oriso-tropic/anisotropic conductive adhesives.

Contact pads 220, 222 on the respective flexible circuit members 210,212 are singulated. Adhesive 221 can optionally be used to bond contactpads 220, 222 to the raised compliant material 202, 204. The flexiblecircuit members 210, 212 can optionally be bonded to the carrier 206.The resulting compliant interconnect assembly 200 is interposed betweenfirst and second circuit members 226, 228 in a compressive relationshipso that contact pads 220, 222 are compressively engaged with respectivecontact pads 230, 232.

FIG. 14A illustrates an alternate compliant interconnect assembly 300 inaccordance with the present invention. The raised compliant material 302is located on the first circuit member 304. The raised compliantmaterial 302 can be bonded to both the first circuit member 304 and therear of contact pad 314. In the illustrated embodiment, the firstcircuit member 304 is a packaged integrated circuit device. The firstcircuit member 304 can alternately be a printed circuit board, anotherflexible circuit, a bare-die device, an integrated circuit device, anorganic or inorganic substrate, a rigid circuit and virtually any othertype of electrical component. Solder ball pad 306 on the flexiblecircuit member 308 is electrically coupled to contact pad 310 on thefirst circuit device 304 by solder ball 312. Contact pad 314 on theflexible circuit member 308 is supported by raised compliant material302. The contact pad 314 can be compressively engaged with pad 316 onthe second circuit member 318.

In an alternate embodiment, FIG. 14A illustrates a connector-on-package320 in accordance with the present invention. The first circuit device304 forms a substrate for package 322 containing bare die device 324. Inthe illustrated embodiment, the bare die device 324 is a flip chipand/or wire bond integrated circuit structure, although any packagedintegrated circuit device can be used in the present connector onpackage 320 embodiment. The compliant interconnect assembly 300 isformed on the substrate 304 as discussed above, yielding a packagedintegrated circuit 324 with an integral connector 300.

FIG. 14B illustrates an alternate compliant interconnect assembly 300Bgenerally as shown in FIG. 14A. Contact pad 305B on the flexible circuitmember 308B is electrically coupled directly to the contact pad 310B onthe first circuit member 304B. The raised compliant material 302B isattached to the circuit member 304B and is reduced in height tocompensate for the height loss due to removal of the solder ball. Thefirst circuit member 304B can be a printed circuit board, anotherflexible circuit, a bare-die device, an integrated circuit device, anorganic or inorganic substrate, a rigid circuit and virtually any othertype of electrical component.

FIG. 15A illustrates an alternate compliant interconnect assembly 400 inaccordance with the present invention. Raised compliant material 402 ismounted on a carrier 404 that is positioned adjacent to the firstcircuit member 406. In the illustrated embodiment, the first circuitmember 406 is a packaged integrated circuit device. The carrier 404 canbe optionally bonded to the first circuit member 406. Ball grid array(BGA) solder ball 408 (or solder paste) is used to electrically couplecontact pad 410 on the first circuit member 406 with the solder ball pad412 on the flexible circuit member 414. The singulated contact pad 416on the flexible circuit member 414 is supported by the raised compliantmaterial 402 for compressive engagement with contact pad 418 on thesecond circuit member 420.

In one application, the embodiment of FIG. 15A can be used to“connectorize” a conventional BGA device 422 by adding the compliantinterconnect assembly 400. In essence, the compliant interconnectassembly 400 can be merged into an existing BGA device 422 to form anassembly 401 comprising the packaged integrated circuit 406 and thecompliant interconnect assembly 400. The contact pads 416 can simply bepushed against the PCB 420 to create a solderless connection withoutactually mounting a connector on the PCB 420. Alternately, solder at theinterface of the contact pads 416, 418 can be reflowed. The assembly 401can be provided as a conversion kit for integrated circuit devices,thereby eliminating the need for a connector on the printed circuitboard 420. The connectorized embodiment of FIG. 15A can be used with anytype of packaged integrated circuit, such as an LGA, PLCC, PGA, SOIC,DIP, QFP, LCC, CSP, or other packaged or unpackaged integrated circuits.

FIG. 15B illustrates an alternate connectorized integrated circuitdevice 424 in accordance with the present invention. The compliantinterconnect 434 includes raised compliant material 425 mounted on acarrier 426. Singulated contact pad 427 on flexible circuit member 428is supported by the raised compliant material 426 for compressiveengagement with contact pad 429 on the first circuit member 430. Theconnection between the contact pads 427, 429 can be created bycompression or the reflow of solder. Integrated circuit device 431 isdirect connected to the flexible circuit member 428. The integratedcircuit device 431 can be electrically coupled to the flexible circuitmember 428 by flip chip bumps 432 and/or wire bonds 433. Alternatively,terminals 436 on the integrated circuit device 431 can include locationsof weakness (see FIG. 10A) that permit the bumps 432 to be snap-fit withthe flexible circuit member 428 (see FIG. 19). The integrated circuitdevice can be an unpackaged bare die device. In one embodiment, theintegrated circuit device 431, the compliant interconnect 434 and aportion of the flexible circuit member 428 can be retained in package435.

FIG. 16 is a perspective view of a replaceable chip module 440 coupledto a flexible circuit member 454 using a compliant interconnect assemblyin accordance with the present invention. The housing 442 includes aplurality of device sites 444, 446, 448, 450 configured to receivevarious first circuit members. The housing 442 can be an insulatorhousing or an alignment frame, typically constructed from plastic orshielded metal.

In one embodiment, the replaceable chip module 440 illustrated in FIG.16 includes a second circuit member 451, such as a PCB, having a 168DIMM edge card connector 452 along one edge. Flex circuit member 454 isinterposed between the second circuit member 451 and the housing 442 toform compliant interconnect assemblies 458 at one or more of the devicesites 444, 446, 448, 450. Various integrated circuit devices can belocated at the device sites 444, 446, 448, 450. The flexible circuitmember 454 may extend across the entire second circuit member 451, orjust a portion thereof. Any of the compliant interconnect assembliesdisclosed herein can be used for this purpose. The raised compliantmaterial can correspondingly be formed on the first or second circuitmembers, or the substrate (see for example FIG. 5).

In another embodiment, the second circuit member 451 is an extension ofthe flexible circuit member 454. Stiffener 443 is optionally providedbehind the flexible circuit member 451.

The housing 442 includes a device site 444 for receiving amicroprocessor device. Along one edge of the housing 442 are a series ofdevice sites 446 configured to receive flash memory integrated circuitdevices. Device sites 448, 450 are provided along the other edges of thehousing 442 for receiving other circuit members supportive of themicroprocessor. Each of the device sites 444, 446, 448, 450 optionallyinclude appropriate covers 456 a-456 c. The covers 456 a-456 c havebeveled edges 449 for sliding engagement with a corresponding lips 453on the housing 442.

The flexible circuit member 454 extends beyond the housing 442,permitting it to perform more functions than simple providing aninterconnect between the first and second circuit members. For example,the flexible circuit member 454 can include integrated ground planes;buried passive functions such as capacitance; redistribution of terminalrouting or pitch; and/or leads to bring in other signals or power fromexternal sources to the device being connected without having to come inthrough the PCB 451. Using the flexible circuit member to perform otherfunctions reduces the number of terminals need to be connected to themain PCB 451 since all of the ground pins from the first circuit memberscan be coupled to the flex circuit and/or the substrate. Anotheradvantage of this embodiment is that it is possible to alter the signalsor power coming in through the flexible circuit member 454, such asfiltering, amplifying, decoupling etc.

FIG. 17 is a side sectional view of an assembly 468 comprising multiplecompliant interconnect assemblies 470, 472 arranged in a stackedconfiguration with multiple circuit members 474, 476, 478 in accordancewith the present invention. The interconnect assemblies 470, 472correspond generally with those illustrated in FIG. 6, although any ofthe interconnect assemblies disclosed herein can be arranged in astacked configuration. The circuit members 474, 476, 478 can be printedcircuit boards, flexible circuits, bare-die devices, integrated circuitdevices, organic or inorganic substrates, rigid circuits or combinationsthereof. The assembly 468 is typically located in a housing (see FIG.16) to maintain alignment and a compressive relationship with thevarious components. The four flexible circuit members 480, 482, 484, 486can be arrange parallel to each other or at various angles.Additionally, the flexible circuit members 480, 482, 484, 486 can beconnected to each other, such as the connection 498 connecting flexiblecircuit member 482 to flexible circuit member 484. FIG. 18 illustratesone possible arrangement of the flexible circuit members 480, 482, 484,486 layered together with the circuit member 474 on top of the assembly468. Distal ends 490, 492, 494, 496 of the various flexible circuitmembers 480, 482, 484, 486 are free to connect to other circuits.

FIG. 19 illustrates an alternate compliant interconnect assembly 500using a compliant interconnect generally as illustrated in FIG. 12A.

Raised compliant material 502 is attached to a carrier 504 that isinterposed between first and second circuit members 506, 508. Thecarrier 504 can be rigid or flexible. An additional support layer 510can optionally be added to the carrier 504 to increase rigidity and/orcompliance. Flexible circuit member 512 is electrically coupled to thecontact pad 514 on second circuit member 508 by solder ball or solderpaste 516. When the first circuit member 506 is compressively engagedwith the compliant interconnect assembly 500, raised compliant material502 biases contact pad 518 on the flexible circuit member 512 againstcontact pad 520 on the first circuit member 506.

In one embodiment, the flexible circuit member 512 extends to a thirdcircuit member 522. The third circuit member 522 can be electricallycoupled using any of the techniques disclosed herein, including theconnectorized approach illustrated in FIG. 15B. In the illustratedembodiment, terminals 524 on the flexible circuit 512 include anaperture 526 and a plurality of locations of weakness 528 (see FIG.10A). The locations of weakness 528 permit solder ball 530 to snap-fitinto aperture 526 to form a strong mechanical interconnect. The solderball 530 can optionally be reflowed to further bind with the terminal524. If the solder ball 530 is reflowed, the segmented portions of theterminal 524 will flex into the molten solder. When the soldersolidifies, the terminal 524 will be at least partially embedded in thesolder ball 530. The third circuit member 522 can be an integratedcircuit device, such as an LGA device, BGA device, CSP device, flipchip, a PCB or a variety of other devices.

FIG. 20 is a schematic illustration of various conductive structures 556formed on the contact pads 554 of flexible circuit member 550.

The conductive structures 556 facilitate electrical coupling withvarious types of contact pads on a circuit member. The structures 556can be metal pieces soldered to the contact pads 554, a build-up ofsolder or conductive adhesive or other conductive members bonded to thecontact pads 554. Structures 560 and 562 include generally flat uppersurfaces 564 suitable to engage with an LGA device. Structure 566includes a recess 568 generally complementary to the contact pads on aBGA device. Structure 570 includes a series of small protrusions 572designed to frictionally engage with various contact pads. Structure 558is a solder bump, such as may be found on a BGA device. The conductivestructures 556 can be coupled with a circuit member using compressionand/or reflowing the solder.

FIG. 21 illustrates an alternate compliant interconnect assembly 600using an electrical trace 602 generally as illustrated in FIGS. 10D-10I.The electrical trace 602 is attached to carrier 604. The carrier 604 canbe a rigid or a flexible dielectric material. After the electrical trace602 is singulated, a second dielectric carrier 606 can optionally belocated on the opposite surface. Distal ends 608 of the compliantmembers 610 are deformed to extend through openings 612 in the carrier604.

In the illustrated embodiment, the distal end 608 is deformed in a firstdirection and a solder ball 614 is electrically coupled to the proximalend of the compliant member 610. When a first circuit member 616 iscompressively engaged with the compliant interconnect assembly 600,distal end 608 of the compliant member 610 electrically couples withcontact pad 618 on the first circuit member 616. Solder ball 614 ispreferably melted to electrically couple with contact pad 620 on secondcircuit member 622. The embodiment of FIG. 21 is particularly suited toreleasably attaching a bare die device 616 to a printed circuit board622.

The compliant interconnect assembly 600 is typically constructed byetching electrical trace 602. A photoresist is printed onto tie barsthat are to be removed. The distal ends 608 are then deformed and theelectrical trace 602 is plated. The photoresist is then removed and theelectrical trace 602 is laminated to the carrier 604. An acid bath isused to etch away the tie bars that were previously covered with thephotoresist. The carrier 604 holds the compliant members 610 inposition. The second dielectric carrier 606 is then optionally laminatedto the opposite side of the electrical trace 602.

FIG. 22 illustrates an alternate compliant interconnect assembly 630using an electrical trace 632 generally as illustrated in FIGS. 10F-I.The electrical trace 632 is attached to carrier 634. After theelectrical trace 632 is singulated, a second dielectric carrier 636 canoptionally be located on the opposite surface. In the embodiment of FIG.22, each compliant member 638 includes at least two distal ends 640,642. The distal end 640 is deformed to extend through openings 644 inthe carrier 634 and the distal end 642 is deformed to extend through theopening 646 in the carrier 636.

When a first circuit member 648 is compressively engaged with thecompliant interconnect assembly 630, distal end 640 electrically coupleswith contact pad 650 on the first circuit member 648. Similarly, asecond circuit member 652 can be compressively engaged with the distalend 642 to electrically couples with contact pad 654 on the secondcircuit member 652.

FIGS. 23 and 24 illustrate a compliant interconnect assembly 660 with afirst electrical trace 662 attached to carrier 664. The first electricaltrace 662 is singulated and the distal ends 666 of the compliant members668 are deformed. Similarly, a second electrical trace 670 is attachedto a carrier 672, singulated and the distal ends 674 of the compliantmembers 676 deformed. The electrical traces 662, 670 are placed in aback to back configuration so that the respective compliant members 668,676 are electrically coupled.

In the embodiment of FIG. 23, the compliant members 668, 674 includeholes 686, 688 that can be electrically coupled using a mechanicalconnection such as a conductive plug or rivet, a heat stake, spot orultrasonic welding, solder, compression, a coined feature that flattensagainst the opposing compliant member, electrical plating, or a varietyof other methods.

In the embodiment of FIG. 24, the compliant members 668, 676 areelectrically coupled by melting solder 690 between the joint, using thecarriers 664, 672 as a solder mask to prevent solder from wicking up thedistal ends 666, 674. Alternatively, the compliant members 668, 676 canbe electrically coupled using compression, solder paste, conductiveadhesive, spot or ultrasonic welding, a coined feature that flattensagainst the opposing compliant member, or a variety of other techniques.In one embodiment. The distal ends 666, 674 are electrically coupledwith contact pads 678, 680 on respective first and second circuitmembers 682, 684, as discussed in connection with FIGS. 21 and 22.

FIG. 25 illustrates an alternate compliant interconnect assembly 700generally as illustrated in FIG. 21, except that an additional circuitryplane 702 is added to the structure. For example, the circuitry plane702 can be a power plane, a ground plane, or a connection to an externalintegrated circuit device 704. The circuitry plane 702 is preferablyelectrically isolated between carriers 708, 710, although some of thecompliant members 713 can be electrically coupled to the circuitry plane702. Optional carrier 706 can be provided. In the illustratedembodiment, the circuitry plane 702 extends beyond the boundaries of thecompliant interconnect assembly 700 to facilitate connection to a powersource, a ground plane, or an external devices 704. For example, thecompliant interconnect assembly 700 can be inserted into the replaceablechip module 400 of FIG. 16, electrically coupling the circuitry plane702 to the flexible circuit member 454 or the edge card connector 452.

As discussed in connection with FIG. 10E, a portion of the electricaltrace 712 can serve as a ground plane or power plane in someembodiments. The present compliant interconnect assembly 700 providesfor internal or embedded passive features such as decoupling capacitanceas a result of the layered power plane 702 and the ground plane providedby a portion of the electrical trace 712. In yet another embodiment,discrete electrical components 714, such as capacitors, can be added tothe present compliant interconnect assembly 700. The circuitry plane 702of the present embodiment improves the operating performance of thefirst and second circuit members 716, 718.

FIG. 26 illustrates an alternate compliant interconnect assembly 750generally as illustrated in FIGS. 23 and 24, except that an additionalcircuitry plane 752 is added to the structure. Again, the circuitryplane 752 can be a power plane, a ground plane, or a connection to anexternal integrated circuit device 754. The circuitry plane 752preferably extends beyond the boundaries of the compliant interconnectassembly 750 to facilitate connection to a power source or externaldevices 754. The circuitry plane 752 is preferably electrically isolatedbetween dielectric layers 762, 764. The present compliant interconnectassembly 750 provides for internal or embedded passive features such asdecoupling capacitance as a result of the layered power plane 752 andthe ground plane provided by a portion of the electrical traces 756,758. Discrete electrical components 760, such as capacitors, canoptionally be added to the present compliant interconnect assembly 750.

FIG. 27 illustrates an alternate compliant interconnect assembly 770generally as illustrated in FIG. 22, except that an additional circuitryplane 772 is added to the structure. Again, the circuitry plane 772 canbe a power plane or a connection to an external integrated circuitdevice 774. The circuitry plane 772 preferably extends beyond theboundaries of the compliant interconnect assembly 770 to facilitateconnection to a power source or external devices 774. The presentcompliant interconnect assembly 770 provides for internal or embeddedpassive features such as decoupling capacitance as a result of thelayered power plane 772 and the ground plane provided by a portion ofthe electrical traces 776 attached to carrier 782. The circuitry plane772 is preferably sandwiched between layers of dielectric material 778,780. Discrete electrical components 784, such as capacitors, canoptionally be added to the present compliant interconnect assembly 770.

FIGS. 28A-28D illustrate various aspects of an alternate compliantinterconnect assembly 800 in accordance with the present invention. Asdiscussed in connection with FIGS. 21-27, the flexible circuit member ispreferably attached to a carrier before singulation so to retain thespatial relationship of the compliant members (see FIGS. 10D-10I). Inthe embodiment of FIGS. 28A-28D, the flexible circuit member, which istypically a sheet of conductive material, is singulated prior toattachment to carrier 806 to form a plurality of discrete compliantmembers 804. The discrete compliant members 804 are attached to acarrier 806 using a variety of techniques, such as thermal or ultrasonicbonding, adhesives, mechanical attachment, and the like.

In the illustrated embodiment, the carrier 806 includes pairs ofadjacent slots 808, 810. Center portion 812 of the carrier 806 betweenthe slots 808, 810 acts as a torsion bar. A discrete compliant member804 is inserted though the slot 808 and attached to the center portion812, preferably by crimping. Alternatively, the compliant members 804can be attached to the carrier 806 through single slot 814. Upper andlower dielectric layers 816, 818 are preferably added to the top andbottom of the compliant interconnect assembly to prevent shorting orcontact rollover during compression. An additional circuitry plane 820and dielectric covering layer 822, as discussed above, can also be addedto the present compliant interconnect assembly 800.

As best illustrated in FIGS. 28C and 28D, the center portion 812 twistsand/or deforms to permit the compliant members 804 to compensate fornon-planarity in the first and second circuit members 824, 826 (see FIG.28 a). Distal ends 828, 830 of the compliant members 804 also flex whencompressed by the first and second circuit members 824, 826. The amountof displacement and the resistance to displacement can be adjusted bychanging the size and shape of the center portion 812 on the carrier806, and/or by constructing the carrier 806 from a more rigid or lessrigid material that resists displacement of the compliant members 804.In one embodiment, a flexible circuit member, such as shown in FIGS.10D-10I is attached to the carrier 806. The combination of the flexiblecircuit member and the discrete compliant members provides maximumflexibility in constructing the present compliant interconnect assembly800.

FIG. 29 illustrates a variation of the compliant interconnect assembly800 of FIGS. 28A-28D. The compliant interconnect assembly 840 includes aplurality of discrete compliant members 842 attached to a carrier 844 asdiscussed above. Distal end 846 is positioned to electrically couplewith contact pad 848 on first circuit member 850. Solder ball 852replaces the distal end 830 in FIG. 28A. The solder ball 852 ispositioned to electrically couple with contact pad 854 on second circuitmember 856.

FIG. 30 is a top view of a compliant interconnect assembly 900 as shownin FIGS. 21-29. Carrier 902 includes an array of holes 904 through whichdistal ends of the compliant members extend to engage with circuitmembers (see FIGS. 21-29). Any additional circuit planes (see FIGS.25-26) are preferably ported from the side of the compliant interconnectassembly 900, preferably by flexible circuit members 906, 908.

The embodiments disclosed herein are basic guidelines, and are not to beconsidered exhaustive or indicative of the only methods of practicingthe present invention. There are many styles and combinations ofproperties possible, with only a few illustrated. Each connectorapplication must be defined with respect to deflection, use, cost,force, assembly, & tooling considered.

Patents and patent applications disclosed herein, including those citedin the background of the invention, are hereby incorporated byreference. Other embodiments of the invention are possible. It is to beunderstood that the above description is intended to be illustrative,and not restrictive. Many other embodiments will be apparent to those ofskill in the art upon reviewing the above description. The scope of theinvention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

1. A compliant interconnect assembly adapted to electrically couple afirst circuit member to a second circuit member, the compliantinterconnect assembly comprising: a first dielectric layer having afirst major surface and a plurality of through openings; a plurality ofelectrical traces positioned against the first major surface of thefirst dielectric layer, the electric traces comprising a plurality ofconductive compliant members having first distal ends aligned with aplurality of the openings in the first dielectric layer, the firstdistal ends adapted to electrically couple with the first circuitmember; and a second dielectric layer having a first major surfacepositioned against the electric traces and the first major surface ofthe first dielectric layer, the second dielectric layer having aplurality of through openings through which the electric traceselectrically couple with the second circuit member.
 2. The compliantinterconnect assembly of claim 1 wherein at least a portion of the firstdistal ends are deformed to project through an opening in the firstdielectric layer.
 3. The compliant interconnect assembly of claim 1wherein at least a portion of the first distal ends extend above asecond major surface of the first dielectric layer.
 4. The compliantinterconnect assembly of claim 1 wherein at least a portion of the firstdistal ends comprise a plurality of distal ends.
 5. The compliantinterconnect assembly of claim 1 wherein at least a portion of the firstdistal end comprises a curvilinear shape.
 6. The compliant interconnectassembly of claim 1 wherein at least a portion of the conductivecompliant member comprises first distal ends deformed to project intoopenings in the first dielectric layer and second distal ends deformedto project into openings in the second dielectric layer.
 7. Thecompliant interconnect assembly of claim 1 comprising at least a portionof the conductive compliant members comprise second distal ends alignedwith a plurality of the openings in the second dielectric layer, thesecond distal ends adapted to electrically couple with the secondcircuit member.
 8. The compliant interconnect assembly of claim 1wherein the electrical traces are attached to the first major surface ofthe first dielectric layer.
 9. The compliant interconnect assembly ofclaim 1 wherein the electrical traces are attached to a flexible circuitmember.
 10. The compliant interconnect assembly of claim 1 comprising asolder ball attached to the electrical traces to electrically couplewith the second circuit member.
 11. The compliant interconnect assemblyof claim 1 comprising an additional circuitry plane attached to a secondmajor surface of the second dielectric layer, the additional circuitryplane comprising a plurality of through openings aligned with aplurality of the through openings in the second dielectric layer. 12.The compliant interconnect assembly of claim 11 wherein the additionalcircuitry plane comprises one of a ground plane, a power plane, or anelectrical connection to other circuit members.
 13. The compliantinterconnect assembly of claim 12 comprising one or more discreteelectrical components electrically coupled to the electrical traces. 14.The compliant interconnect assembly of claim 13 wherein the one or morediscrete electrical components comprise capacitors.
 15. The compliantinterconnect assembly of claim 1 wherein a portion of the firstelectrical traces extends beyond the compliant interconnect assembly topermit electrical coupling with another circuit member.
 16. Thecompliant interconnect assembly of claim 1 wherein the electrical tracesare singulated so that a portion of the conductive compliant members areelectrically isolated from the electrical traces.
 17. The compliantinterconnect assembly of claim 1 wherein a portion of the conductivecompliant members are electrically coupled to form a ground plane or apower plane.
 18. The compliant interconnect assembly of claim 1 whereinthe first distal ends of the conductive compliant members are adapted toengage with a connector member selected from the group consisting of aflexible circuit, a ribbon connector, a cable, a printed circuit board,a ball grid array (BGA), a land grid array (LGA), a plastic leaded chipcarrier (PLCC), a pin grid array (PGA), a small outline integratedcircuit (SOIC), a dual in-line package (DIP), a quad flat package (QFP),a leadless chip carrier (LCC), a chip scale package (CSP), or packagedor unpackaged integrated circuits.
 19. The compliant interconnectassembly of claim 1 wherein the second dielectric layer is attached to aprinted circuit board and a plurality of the conductive compliantmembers are electrically coupled to contact pads on the printed circuitboard through the openings in the second dielectric layer.
 20. Thecompliant interconnect assembly of claim 1 wherein a portion of thefirst electrical traces extend beyond the compliant interconnectassembly to form a stacked configuration other compliant interconnectassemblies.
 21. The compliant interconnect assembly of claim 1 whereinthe dielectric layer comprises a rigid material.
 22. The compliantinterconnect assembly of claim 1 wherein the dielectric layer comprisesa flexible material.
 23. The compliant interconnect assembly of claim 1wherein the plurality of electrical traces comprises: a first set ofelectrical traces having a plurality of conductive compliant membershaving first distal ends aligned with a plurality of openings in thefirst dielectric layer; a second set of electrical traces having aplurality of conductive compliant members having second distal endsaligned with a plurality of openings in the second dielectric layer; andan electrical connection between one or more of the conductive compliantmembers on the first set of electrical traces and one or more of theconductive compliant members on the second set of electrical traces. 24.The compliant interconnect assembly of claim 23 comprising a dielectriclayer located between the first and second sets of electrical traces.25. The compliant interconnect assembly of claim 23 wherein theelectrical connection comprises one of solder, a conductive plug, aconductive rivet, conductive adhesive, a heat stake, spot weld, andultrasonic weld, a compression joint, or electrical plating.
 26. Thecompliant interconnect assembly of claim 23 comprising an additionalcircuitry plane located between the first and second sets of electricaltraces.
 27. The compliant interconnect assembly of claim 26 wherein atleast one major surface of the additional circuitry plane comprises oneof a dielectric layer, a printed circuit board, a flexible circuit, abare die device, an integrated circuit device, organic or inorganicsubstrates, or a rigid circuit.
 28. The compliant interconnect assemblyof claim 23 comprising one or more discrete electrical componentslocated between the first and second sets of electrical traces.
 29. Acompliant interconnect assembly comprising: a first circuit member; asecond circuit member; a first dielectric layer having a first majorsurface and a plurality of through openings; a plurality of electricaltraces positioned against the first major surface of the firstdielectric layer, the electric traces comprising a plurality ofconductive compliant members having first distal ends aligned with aplurality of the openings in the first dielectric layer, the firstdistal ends adapted to electrically couple with the first circuitmember; and a second dielectric layer having a first major surfacepositioned against the electric traces and the first major surface ofthe first dielectric layer, the second dielectric layer having aplurality of through openings through which the electric traceselectrically couple with the second circuit member.
 30. The compliantinterconnect assembly of claim 29 wherein the first circuit membercomprises one of a printed circuit board, a flexible circuit, a bare diedevice, an integrated circuit device, organic or inorganic substrates,or a rigid circuit.
 31. A method of making a compliant interconnectassembly, the method comprising the steps of: positioning a plurality ofelectrical traces against the first major surface of a first dielectriclayer, the electric traces comprising a plurality of conductivecompliant members having first distal ends aligned with a plurality ofthrough openings in the first dielectric layer; positioning a firstmajor surface of a second dielectric layer against the electric tracesand the first major surface of the first dielectric layer, the seconddielectric layer having a plurality of through openings; electricallycoupling the first distal ends to a first circuit member; andelectrically coupling a second circuit member to a second circuit memberthrough the openings in the second dielectric layer.
 32. The method ofclaim 31 comprising positioning at least a portion of the first distalends to project through an opening in the first dielectric layer. 33.The method of claim 31 comprising positioning at least a portion of thefirst distal ends above a second major surface of the first dielectriclayer.
 34. The method of claim 31 comprising: positioning at least aportion of the first distal ends to project into openings in the firstdielectric layer; and positioning second distal ends of the conductivecompliant members to project into openings in the second dielectriclayer.
 35. The method of claim 34 comprising electrically coupling thesecond circuit member with the second distal ends of the conductivecompliant members.
 36. The method of claim 31 comprising attaching theelectrical traces to the first major surface of the first dielectriclayer.
 37. The method of claim 31 comprising attaching the electricaltraces to a flexible circuit member.
 38. The method of claim 31comprising attaching a solder ball to the electrical traces toelectrically couple with the second circuit member.
 39. The method ofclaim 31 comprising locating an additional circuitry plane along asecond major surface of the second dielectric layer, the additionalcircuitry plane comprising a plurality of through openings aligned witha plurality of the through openings in the second dielectric layer. 40.The method of claim 39 wherein the additional circuitry plane comprisesone of a ground plane, a power plane, or an electrical connection toother circuit members.
 41. The method of claim 39 comprising locatingone or more discrete electrical components between the first and seconddielectric layers and electrically coupled to the electrical traces. 42.The method of claim 31 comprising singulating at least a portion of theelectrical traces.
 43. The method of claim 31 comprising electricallycoupling a portion of the conductive compliant members to form a groundplane or a power plane.
 44. The method of claim 31 comprising formingthe first distal ends of the conductive compliant members to engage witha connector member selected from the group consisting of a flexiblecircuit, a ribbon connector, a cable, a printed circuit board, a ballgrid array (BGA), a land grid array (LGA), a plastic leaded chip carrier(PLCC), a pin grid array (PGA), a small outline integrated circuit(SOIC), a dual in-line package (DIP), a quad flat package (QFP), aleadless chip carrier (LCC), a chip scale package (CSP), or packaged orunpackaged integrated circuits.
 45. The method of claim 31 comprising:attaching the second dielectric layer to a printed circuit board;electrically coupling a plurality of the conductive compliant members tocontact pads on the printed circuit board through the openings in thesecond dielectric layer.
 46. The method of claim 31 comprising forming aplurality of the compliant interconnect assemblies into a stackedconfiguration.
 47. The method of claim 31 comprising selecting the firstand second circuit members from one of a dielectric layer, a printedcircuit board, a flexible circuit, a bare die device, an integratedcircuit device, organic or inorganic substrates, or a rigid circuit. 48.The method of claim 31 comprising the steps of: aligning a first set ofelectrical traces having a plurality of conductive compliant memberswith first distal ends with a plurality of openings in the firstdielectric layer; aligning a second set of electrical traces having aplurality of conductive compliant members with second distal ends with aplurality of openings in the second dielectric layer; and electricallycoupling one or more of the conductive compliant members on the firstset of electrical traces with one or more of the conductive compliantmembers on the second set of electrical traces.
 49. The method of claim48 comprising locating a dielectric layer between the first and secondsets of electrical traces.
 50. The method of claim 48 comprisingelectrically coupling one or more of the conductive compliant members onthe first set of electrical traces with one or more of the conductivecompliant members on the second set of electrical traces using one ofsolder, a conductive plug, a conductive rivet, conductive adhesive, aheat stake, spot weld, and ultrasonic weld, a compression joint, orelectrical plating.
 51. The method of claim 48 comprising locating anadditional circuitry plane between the first and second sets ofelectrical traces.
 52. The method of claim 48 comprising locating one ormore discrete electrical components between the first and second sets ofelectrical traces.